A dead crow found in Greenbrier State Park near Boonsboro last week tested positive for West Nile virus, the Maryland Department of Health and Mental Hygiene said Tuesday.
It was Washington County's first confirmed case of the disease, said Rod MacRae, the Washington County Health Department's administrator.
MacRae said a park employee found the dead crow Aug. 6. A Washington County environmental health sanitarian collected the bird and sent it to a state lab in Baltimore for testing, he said.
Infected mosquitoes carrying the West Nile virus can spread it by biting a human, animal or bird.
In humans, symptoms of the virus are usually mild, but the most severe cases can be fatal, according to the U.S. Centers for Disease Control and Prevention's Division of Vector-Borne Infectious Diseases.